JP2013247021A - Display device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device which achieves high reliability, and to provide a manufacturing method which enables the display device to be manufactured with high yield.SOLUTION: A display device includes: a substrate 10; an organic light emitting element 20 formed on the substrate 10; a first protection layer 31 coating the organic light emitting element 20; and a second protection layer 32 provided on the first protection layer 32 and covering the organic light emitting element 20. The first protection layer 31 includes an inclined part formed by a foreign object existing on the organic light emitting element 20 and a level difference absorbing part is selectively provided around the inclined part. The second protection layer 32 coats the first protection layer 31 and the level difference absorbing part. The level difference absorbing part is a member that is selectively formed around the inclined part of the first protection layer 31 by etching an intermediate layer formed on the first protection layer 31. The second protection layer 32 is formed on the first protection layer 31 and the level difference absorbing part.

Description

  The present invention relates to a display device, in particular, a display device having an organic light emitting element, and a method for manufacturing the display device.

  An organic light emitting device (organic EL (electroluminescence) device) is an electronic device in which a thin-film organic compound layer including at least a light emitting layer is disposed between a first electrode and a second electrode. An organic light-emitting element is known as an electronic element that can emit light with high luminance by injecting a current between a first electrode and a second electrode. On the other hand, an organic light-emitting device composed of a first electrode, an organic compound layer, and a second electrode has a property that it is vulnerable to moisture (water vapor) and oxygen in the air. That is, it is known that when an organic light emitting device is left in the air, a spot-like non-light emitting portion (dark spot) is generated in the region where the organic compound layer is formed due to moisture or oxygen in the air. Yes. The reason why the non-light emitting portion is generated is that a defect such as a pinhole may occur in the electrode layer formed on the organic compound layer, and moisture and oxygen enter the organic compound layer and the like through the defect. it is conceivable that. For this reason, when manufacturing an organic light emitting device, it is necessary to seal the device itself for the purpose of preventing intrusion of moisture and oxygen after forming a member constituting the device.

  Here, when sealing an organic light emitting element, conventionally, after forming a second electrode (upper electrode) which is a constituent member of the organic light emitting element, a method of forming a sealing film on the second electrode Was known. However, when forming a sealing film, if foreign matter or a pattern step or the like is generated in the lower layer (second electrode or the like) of the sealing film, the place where the sealing property is low due to these foreign matter or pattern step ( (Spots with irregularities on the surface) may occur. When an attempt is made to form a sealing film at a location where the sealing performance is low, defects such as cracks that cause a reduction in the function of the sealing film occur at this location. Here, as a method of reducing defects in the sealing film, there is a method of forming a film so that the film thickness of the sealing film is equal to or greater than the height of a foreign substance, etc. The problem of high costs arises. In addition, increasing the thickness of the sealing film causes other problems such as a decrease in light transmittance and an increase in film stress. In addition, when mass-producing organic light-emitting elements, there is almost no reproducibility about the size and shape of foreign substances etc. that can exist on the second electrode, etc., so the sealing film necessary for producing with a stable yield There is also a problem that it is difficult to estimate the film thickness.

  As a method for solving the problems related to the sealing film described above, for example, a method disclosed in Patent Document 1 has been proposed. In Patent Document 1, a barrier stack including at least one decoupling layer and at least one barrier layer is employed. Here, the decoupling layer is a layer for flattening the surface of the lower layer. On the other hand, the barrier layer is a layer for blocking moisture and oxygen in the atmosphere, and covers the end of the decoupling layer that takes in moisture and oxygen. Here, when two layers of the barrier stack adopted in Patent Document 1 are laminated, the second barrier layer is formed by the second decoupling layer provided immediately below the first barrier layer. Can be formed under conditions with good surface flatness. As a result, the second barrier layer can be formed as a layer having improved sealing properties than the first barrier layer.

Japanese Patent No. 4303591

  However, since a thin film-like decoupling layer provided between two barrier layers cannot prevent moisture and oxygen from diffusing, if a defect occurs in a part of the barrier layer, the moisture and oxygen are removed from the defect in the decoupling layer. May penetrate and diffuse in the surface direction. If a defect is generated in each of the plurality of barrier layers, there is a risk that moisture or oxygen in the atmosphere propagates through the defect and the decoupling layer and reaches the organic light emitting device. In particular, when a defect occurs in the first barrier layer closest to the organic light emitting device, moisture and oxygen enter the organic light emitting device from the defective portion of the first barrier layer, thereby causing a defect in the first barrier layer. A luminance reduction region is formed around the part. This may cause a display defect such as generation of dark spots. In addition, the barrier layer defects caused by the influence of the surface flatness when forming the barrier layer and the like can be improved by providing a decoupling layer, but if there is a foreign substance on the formed decoupling layer, it becomes a decoupling layer shape. There was a risk of defects in the formed barrier layer.

  Moreover, in the sealing structure currently disclosed by patent document 1, by providing more barrier stacks which consist of a decoupling layer and a barrier layer, a water | moisture content or oxygen moves to the organic light emitting element from the defect of the barrier layer mentioned above. The time (penetration time) can be lengthened. For this reason, the reliability of the display device can be improved. However, when the barrier stack is excessively provided, not only the manufacturing cost is increased, but also other problems such as a decrease in light transmittance and an increase in film stress are caused.

  For this reason, even if the sealing method proposed in Patent Document 1 is adopted, moisture that can enter over a period necessary for guaranteeing the reliability of the display device (for example, 1000 hours in a 60 ° C. and 90% RH environment). And it can be difficult to keep preventing oxygen. It is also important for manufacturing organic light-emitting devices and display devices that the barrier layer with the target reliability is formed at low cost and at the same time the light transmittance of the device itself is increased and the film stress is brought close to zero. It is a difficult issue.

  The present invention is made to solve the above-described problems, and an object of the present invention is to provide a display device with high reliability and a manufacturing method capable of producing the display device with a high yield. is there.

The display device of the present invention includes a substrate,
An organic light emitting device formed on the substrate;
A first protective layer covering the organic light emitting device;
A second protective layer provided on the first protective layer and covering the organic light emitting element,
The first protective layer has an inclined portion due to foreign matter existing on the organic light emitting element,
A step relief portion is selectively provided around the inclined portion,
The second protective layer covers the first protective layer and the step relief portion.

Moreover, the manufacturing method of the display device of the present invention includes a step of forming an organic light emitting element, in which a first electrode, an organic light emitting layer, and a second electrode are formed in this order on a substrate.
Forming a first protective layer so as to cover the organic light emitting element; and
Forming an intermediate layer on the first protective layer; and
An etching step of selectively forming a step relief portion around the inclined portion of the first protective layer by etching the intermediate layer;
And a second protective layer forming step of forming a second protective layer on the first protective layer and on the step relief portion.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which makes it possible to produce a display device with high reliability and this display device with a high yield can be provided.

  That is, since the display device of the present invention has the following two configurations at the same time, a highly reliable display device can be produced with a high yield.

  In the first configuration, when the first protective layer is provided, a step relief portion is selectively provided on the inclined portion of the first protective layer that is formed when foreign matter or a pattern step portion is present below the first protective layer. It is a configuration. Thereby, the coverage of the 2nd protective layer provided on a 1st protective layer is improved compared with a 1st protective layer. Specifically, it is possible to prevent a defect from occurring in the second protective layer formed on the first protective layer by the step relief portion.

  The second configuration is a configuration in which the step height reducing portion is formed by etching and removing the intermediate layer provided on the flat region of the first protective layer. Then, since there is only a partial region of an intermediate layer capable of diffusing moisture and oxygen between the first protective layer and the second protective layer, even if a defect occurs in the second protective layer, Intruded moisture and oxygen can be blocked at the interface between the first protective layer and the second protective layer.

  Furthermore, since the display device of the present invention is provided so that two protective layers (first protective layer and second protective layer) that protect the organic light emitting element from moisture and oxygen in the atmosphere are in contact with each other, the protective member is provided. It is highly reliable despite being a member on a relatively thin film.

It is a cross-sectional schematic diagram which shows the example of embodiment in the display apparatus of this invention. It is a cross-sectional schematic diagram which shows the relationship between the foreign material which may arise in the case of formation of a 1st protective layer, and the 2nd protective layer formed on this foreign material. It is a flowchart which shows the example of the manufacturing process in the manufacturing method of the display apparatus of this invention. It is a cross-sectional schematic diagram which shows the manufacturing process from the formation process of an intermediate | middle layer to the formation process of a 2nd moisture-proof layer.

  First, the display device of the present invention will be described. The display device of the present invention includes a substrate, an organic light emitting element, a first protective layer, and a second protective layer. In the present invention, the organic light emitting device is formed on a substrate. In the present invention, the first protective layer is a protective member that covers the organic light emitting element, and the second protective layer is provided on the first protective layer and covers the organic light emitting element in the same manner as the first protective layer. It is.

  In the present invention, the first protective layer has an inclined portion due to foreign matters existing on the organic light emitting element. Here, a step relief portion is selectively provided around the inclined portion, and the second protective layer covers the first protective layer and the step relief portion, respectively.

  Next, embodiments of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of the display device of the present invention.

  In the display device 1 of FIG. 1, a first electrode (lower electrode, anode electrode) 21, an organic compound layer 22, and a second electrode (upper electrode, cathode electrode) 23 are provided in this order on a substrate 10. The organic light emitting device 20 is provided. In the display device 1 of FIG. 1, two types of protective layers (first protective layer 31 and second protective layer 32) are provided on the organic light emitting element 20, and each cover the organic light emitting element 20.

  1 is provided with one organic light emitting element 20. However, a plurality of organic light emitting elements 20 may be provided, and a plurality of organic light emitting elements 20 having different emission colors may be arranged to form a pixel. It may be configured. The display device 1 of FIG. 1 is a top emission type organic EL display device that extracts light output from the organic compound layer 22 from a second electrode (upper electrode) 23 provided on the opposite side of the substrate 10.

  Hereinafter, components of the display device 1 of FIG. 1 will be described.

  When the display device 1 of FIG. 1 is a top emission type display device, the substrate 10 constituting the display device 1 of FIG. 1 may be a substrate that does not transmit light. As the substrate 10 constituting the display device 1 in FIG. 1, a substrate such as a glass substrate or a metal substrate can be used. Further, a TFT (not shown) is provided in the substrate 10 constituting the display device 1 of FIG. 1 so as to correspond to the first electrode 21 so that the first electrode 21 is electrically connected to the drain electrode of the TFT. May be. In this aspect, the organic light emitting element 20 provided in the target pixel can be caused to emit light independently of other pixels by using the switching function of the TFT.

  When the display device 1 of FIG. 1 is a top emission type organic EL display device, the first electrode 21 is an electrode thin film having light reflectivity. In addition, when the display device 1 of FIG. 1 includes a plurality of organic light emitting elements 20, although not shown, a bank (pixel separation film) is appropriately provided, and the first electrode 21 included in each organic light emitting element is provided by the bank. Each may be divided.

  The organic compound layer 22 which is a constituent member of the display device in FIG. 1 is a laminate composed of one layer or a plurality of layers having at least a light emitting layer. When the organic compound layer 22 is a laminate composed of a plurality of layers, the layers constituting the organic compound layer 22 other than the light emitting layer include a hole injection layer, a hole transport layer, an electron block layer, a hole block layer, Examples thereof include an electron transport layer and an electron injection layer.

  When the display device 1 of FIG. 1 is a top emission type organic EL display device, the second electrode 23 is an electrode thin film having optical transparency. In addition, the light transmittance as used in the field of this invention means transmitting at least 50% of the light output from the organic compound layer 22 (output to the outside).

  In the display device 1 of FIG. 1, the organic light emitting element 20 is covered and sealed with two types of protective layers, that is, a first protective layer 31 and a second protective layer 32. However, in the present invention, the organic light emitting element 20 may be covered with the first protective layer 31 or the second protective layer 32. In such a case, the organic light emitting device 20 is preferably covered with the second protective layer 32 having a relatively small number of defects.

  FIG. 2 is a schematic cross-sectional view showing the relationship between a foreign substance that may exist during the formation of the first protective layer and the second protective layer formed on the foreign substance. FIG. 2 is also a partially enlarged view of a portion X in FIG.

  The first protective layer 31 formed on the second electrode 23 is formed as a continuous thin film if the surface of the second electrode 23 is smooth. However, as shown in FIGS. 2A and 2B, foreign matter 51 may exist on the surface of the second electrode 23 after the second electrode 23 is formed. 2 (a) and 2 (b) has a substantially spherical shape, but is attached to the second electrode 23 in the actual production process and exists on the surface of the second electrode 23. There are various types of shapes or sizes of the foreign object 51 that can be formed. Here, when the foreign matter 51 exists on the surface of the second electrode 23, when the first protective layer 31 is provided on the second electrode 23, the inclined portion 31 a has a cross-sectional shape (undulation) around the foreign matter 51. It is formed in a corresponding shape. Here, since the inclined portion 31a is a thin film having a smaller film thickness than the first protective layer 31 provided in a region where no foreign matter exists, the first protective layer 31 is locally discontinuous around the foreign matter 51. A thin film. One reason for this is that the first protective layer 31 formed by vacuum film formation is different in the growth rate of the film deposited in the shadowed portion of the foreign matter 51 and the region without the foreign matter. As described above, in the first protective layer 31, cracks are likely to be formed at locations that are locally discontinuous in the vicinity of the inclined portion 31a, and the film density that is considered to be related to moisture permeability tends to decrease. is there. On the other hand, even if the foreign matter 51 is not generated, a step may occur in the second electrode 23 due to a pattern step generated when the wiring or resist structure is formed. This step also causes the inclined portion 31a to be formed.

  Here, in the present invention, when the inclined portion 31a occurs when forming the first protective layer 31, the step height reducing portion 40 is provided only around the inclined portion 31a. In the present invention, the step relief portion 40 has a function of relaxing the inclination angle of the inclined portion 31a and a function of filling a crack or gap that can be formed in the shadow of the foreign matter 51 or in the vicinity of the inclined portion 31a. Yes. However, in the present invention, it is only necessary to provide the step-reducing portion 40 so that the cross-sectional shape around the inclined portion 31a is a forward tapered shape and the inclination angle of the inclined portion 31a can be reduced. For this reason, it is not always necessary to completely fill the cracks and gaps formed in the vicinity of the inclined portion 31a of the first protective layer 31 by the step relief portion 40. That is, in the present invention, it is only necessary that the inclined portion 31a of the first protective layer 31 and the sectional shape of the periphery thereof can be made into a forward tapered shape by relaxing the inclination angle of the inclined portion 31a. Thereby, when providing the 2nd protective layer 32 on the 1st protective layer 31, it is because possibility that a defect will arise in the 2nd protective layer 32 by the inclination part 31a of the 1st protective layer 31 can be reduced.

  In addition, the constituent material of the level | step difference mitigation part 40 is a material with a weak function which interrupts | blocks the water | moisture content and oxygen in air | atmosphere compared with a protective layer (the 1st protective layer 31 and the 2nd protective layer 32). For this reason, the level | step difference relaxation part 40 is provided only around the inclination part 31a. Thereby, the problem regarding the thin film made of the constituent material of the step relaxing portion 40, that is, when a defect occurs in a part of the second protective layer 32, moisture and oxygen in the atmosphere from the defect causes the constituent material of the step relaxing portion 40. The problem about osmosis | permeation in the thin film which consists of can be eliminated.

  The constituent material of the step relief portion 40 is not limited as long as it is a material that has a function of covering the inclined portion 31a of the first protective layer 31 and relaxing the inclination angle of the inclined portion 31a. A material that can be formed using a coating method that can greatly reduce the tilt angle is particularly preferable. Examples of the constituent material of the step reducing portion 40 that can utilize the coating method include materials obtained by organic polymers, inorganic polymers, organometallic polymers, hybrid organic / inorganic polymers, and combinations thereof. However, it is not limited to the polymer material, and the step relief portion 40 can be formed using a coating method by dissolving a low molecular material in an appropriate solvent. In addition, the step relief portion 40 may be a laminated body formed by laminating a plurality of different types of materials. Further, the step relief portion 40 preferably has a transmittance of 80% or more in the visible light region so as not to reduce the light emission efficiency. Further, in order to prevent reflection at the interface between the first protective layer 31 / step difference mitigating portion 40 / second protective layer 32, the step mitigating portion 40 is preferably the first protective layer 31 or the second protective layer. A material is selected so that the difference in refractive index from 32 is small. Further, the constituent material of the step relief portion 40 is an organic compound so that the organic compound layer constituting the organic light emitting element is not damaged when the constituent material of the step relief portion 40 passes through the defect portion of the first protective layer 31. It is desirable that the activity is low with respect to the constituent material of the layer. In the present invention, in order to facilitate the process control, it is desirable that the constituent material of the step reducing portion 40 is a material having a sufficiently high etching rate as compared with the constituent material of the first protective layer 31. In addition, when forming the thin film (intermediate layer mentioned later) used as the level | step difference relaxation part 40, you may provide an etching stop layer on the 1st protective layer 31 beforehand. This makes it possible to perform etching without damaging the first protective layer 31 even if there is not much difference in the etching rate between the constituent material of the first protective layer 31 and the constituent material of the step relief portion 40. .

  Specifically, when an organic polymer is used as a constituent material of the step relief portion 40, urethane, polyamide, polyimide, polybutylene, polyolefin, isobutylene, isoprene, epoxy, parylene, benzocyclobutadiene, polynorbornene, polyallyl ether, polycarbonate , Alkyd resin, polyaniline, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, fluoride polymer, and the like, but are not limited thereto. In the present invention, a plurality of the aforementioned polymers may be used in combination.

  Specifically, when an inorganic polymer is used as a constituent material of the step relief portion 40, silicone, polyphosphazene, polysilazane, polycarbosilane, polycarbosilane, carborane siloxane, polysilane, phosphonitrile polymer, sulfur nitride polymer, siloxane Examples include, but are not limited to, polymers. In the present invention, a plurality of the aforementioned polymers may be used in combination.

  In the case where an organometallic polymer is used as the constituent material of the step relief portion 40, specific examples include organometallic polymers having a typical metal, a transition metal, and a lanthanide / actinide metal as the central metal, but are not limited thereto. is not. In the present invention, the central metal contained in the organometallic polymer may be one kind or two or more kinds.

  In the case where a hybrid organic / inorganic polymer system is used as the constituent material of the step relief portion 40, specifically, organically modified silicate, preceramic polymer, polyimide-silica hybrid, acrylate-silica hybrid, polydimethylsiloxane-silica Including but not limited to hybrids, ceramics, and combinations thereof.

  When a low molecular material is used as the constituent material of the step reducing portion 40, for example, a solution prepared by dissolving an organic EL material such as α-NPD in a toluene solvent or the like is applied and formed as the constituent material of the step reducing portion 40 By doing so, the step relief portion 40 is formed. However, the present invention is not limited to this. The step relief portion 40 can be formed by dry etching an intermediate layer generated by a plurality of well-known processes whose surface flatness is improved, including an atmospheric pressure process and a vacuum process. The method for manufacturing the intermediate layer will be described later.

  As shown in FIGS. 2A and 2B, even when the inclined portion 31a is generated by the foreign matter 51 when the first protective layer 31 is formed, the step relief portion 40 is formed around the inclined portion 31a. Is provided. Since the cross-sectional shape of the inclined portion 31a becomes a forward tapered shape due to the step relief portion 40, when the second protective layer 32 is provided on the first protective layer 31, the second protective layer 32 is formed as a continuous thin film. Defects such as cracks are less likely to occur. For this reason, even if a defect occurs in the first protective layer 31, the organic light emitting device 20 can be sealed by the second protective layer 32 regardless of this defect, and moisture and oxygen enter from above the defect of the first protective layer 31. Can be sufficiently suppressed. In addition, as shown in FIG. 2B, when the second protective layer 32 is formed, the inclined portion 32a of the second protective layer 32 is formed due to the presence of foreign matter 52 or the like on the surface of the first protective layer 31. Thus, even if a partial defect occurs in the second protective layer 32, the first protective layer 31 is located immediately below the defect. For this reason, even if moisture and oxygen in the atmosphere intrude due to defects in the second protective layer 32, these can be blocked by the first protective layer 31 having a function of preventing the entry of moisture and oxygen in the atmosphere.

  In the present invention, each of the two types of protective layers (the first protective layer 31 and the second protective layer 32) may be composed of one layer, or may be a laminate formed by laminating a plurality of layers. . Here, when the protective layer is a laminate, each layer constituting the protective layer can be formed from the same material or different materials.

  The material of the protective layer may be a transparent material or an opaque material depending on the use of the protective layer. In the present invention, suitable materials for the protective layer include, but are not limited to, metal compounds such as simple metals, oxides, nitrides, carbide oxynitrides, and oxyborides. In addition, you may use the metal simple substance and metal compound which were mentioned above in the aspect of the alloy and mixture which combined 2 or more types.

  Examples of simple metals that are suitable materials for the protective layer include, but are not limited to, aluminum, titanium, indium, tin, tantalum, zirconium, niobium, hafnium, yttrium, nickel, tungsten, chromium, and zinc. is not.

  Metal oxides that are suitable for the protective layer include silicon oxide, aluminum oxide, titanium oxide, indium oxide, tin oxide, indium tin oxide, tantalum oxide, zirconium oxide, niobium oxide, hafnium oxide, yttrium oxide, nickel oxide. , Tungsten oxide, chromium oxide, zinc oxide and the like, but are not limited thereto.

  Examples of the metal nitride that is a suitable material for the protective layer include, but are not limited to, aluminum nitride, silicon nitride, boron nitride, germanium nitride, chromium nitride, and nickel nitride.

  Metal carbides that are suitable materials for the protective layer include, but are not limited to, boron carbide, tungsten carbide, silicon carbide, and combinations thereof.

  Metal oxynitrides that are suitable materials for the protective layer include, but are not limited to, aluminum oxynitride, silicon oxynitride, boron oxynitride, and combinations thereof.

  Metal oxyborides that are suitable materials for the protective layer include, but are not limited to, zirconium oxyboride, titanium oxyboride, and combinations thereof.

  In addition to the materials described above, opaque metals, opaque ceramics, opaque polymers, opaque cermets, and the like can also be used as the protective layer material. Moreover, you may use these materials in the aspect which combined multiple types.

  When an opaque cermet is used as the material for the protective layer, specific examples include zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, niobium nitride, tungsten disilicide, titanium diboride, zirconium diboride, and the like. However, it is not limited to these.

Next, a method for manufacturing the display device of the present invention will be described. The manufacturing method according to the present invention has at least the processes shown below.
(1) Step of forming an organic light emitting device that forms a first electrode, an organic light emitting layer, and a second electrode in this order on the substrate. (2) Forming a first protective layer so as to cover the organic light emitting device. Forming the first protective layer (3) forming the intermediate layer on the first protective layer (4) etching the intermediate layer to selectively reduce the step around the inclined portion of the first protective layer Etching step for forming the portion (5) Step of forming the second protective layer for forming the second protective layer on the first protective layer and the step relief portion

  FIG. 3 is a flowchart showing an example of a manufacturing process in the method for manufacturing a display device of the present invention. Hereinafter, each process will be described with reference to the flowchart of FIG. 3 as appropriate.

(1) Formation Step of Organic Light-Emitting Element First, the first electrode 21 is formed on the substrate 10 (first electrode formation step). At this time, a known method such as a photolithography process can be employed as a method of forming the first electrode 21. Next, the substrate 10 is cleaned (substrate cleaning process). Next, after the substrate 10 provided with the first substrate 21 is put into a vacuum atmosphere chamber, a baking process is performed in a vacuum atmosphere, and a pretreatment process of the first electrode 21 is performed by oxygen plasma. Next, an organic compound layer 22 in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order is formed on the first electrode 21 by a vacuum vapor deposition method while maintaining a vacuum atmosphere (organic). Compound layer forming step). In particular, in the step of painting the light emitting layer for each RGB pixel, it is desirable to pattern the light emitting layer using a high-definition vapor deposition mask having openings in regions corresponding to the pixels of each color.

  After the organic compound layer 22 is formed, an electrode layer (second electrode 23) made of a light-transmitting conductive material is formed on the organic compound layer 22 (second electrode forming step). Examples of the constituent material of the second electrode 23 include transparent conductive materials such as indium tin oxide and indium zinc oxide. The second electrode 23 may be a semi-transmissive film formed by forming a thin film made of a metal material such as Ag with a predetermined thickness.

(2) Step of forming first protective layer Next, the first protective layer 31 is formed on the second electrode 23 (step of forming the first protective layer). As a constituent material of the first protective layer 31, at least a material having a function of suppressing permeation of moisture and oxygen, for example, silicon nitride (SiN _x ) or the like is used. The first protective layer 31 is formed by a conventional method such as sputtering, vapor deposition, sublimation, CVD (chemical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), ECR-PECVD (electron cyclotron resonance-plasma enhanced chemical vapor deposition). It can be formed by depositing the constituent material by any suitable process, including a vacuum process, but the process is not limited thereto. Moreover, when forming the 1st protective layer 31, you may use combining several processes mentioned above. The first protective layer 31 is formed in such a film thickness that does not impair the sealing performance after the subsequent etching process (intermediate layer). Specifically, it is desirable that the film thickness of the first protective layer 31 is 0.1 μm to 5 μm, the light transmittance in the visible region is 80% or more, and the film stress is close to zero.

(3) Intermediate Layer Forming Step Next, the intermediate layer 41 is formed on the first protective layer 31 (intermediate layer forming step). FIG. 4 is a schematic cross-sectional view showing the manufacturing process from the step of forming the intermediate layer 41 to the step of forming the second protective layer. 4A is a process for forming the intermediate layer 41, FIG. 4B is an etching process, and FIG. 4C is a process for forming a second protective layer.

  Hereinafter, this process will be described using a case in which polycarbonate is used as the constituent material of the intermediate layer 41 as a specific example.

  First, after preparing a polycarbonate solution (solvent: toluene), the solution is dropped on the first protective layer 31 in a nitrogen atmosphere and spin coating is performed to form a coating film to be the intermediate layer 41. Thus, when the intermediate layer 41 is formed by a coating method typified by spin coating, the solution flows on the substrate 10 or on the defect of the first protective layer 31. For this reason, it is possible to cover the entire first protective layer 31 while filling a low area in the vicinity of the inclined portion 31a of the first protective layer 31 (region where the first protective layer 31 is discontinuous). This is preferable as a method for forming the intermediate layer 41. As a result, in particular, a surface with greatly improved flatness can be obtained in the inclined portion 31a. That is, the intermediate layer 41 has a cross-section around the inclined portion 31a with the inclined portion 31a of the first protective layer 31 caused by the undulation of the foreign matter 51 and the second electrode 23 causing the sealing characteristics of the first protective layer 31 to be significantly impaired. The first protective layer 31 can be coated in a state in which the shape is a forward taper. In addition, the intermediate | middle layer 41 fully excludes the water | moisture content and solvent contained in a layer by pressure reduction heating conditions after film-forming.

  In addition, in order to form the step relief portion 40 in a favorable shape in the inclined portion 31a of the first protective layer 31 and its surroundings in the etching process described later, as shown in FIG. 4A, on the inclined portion 31a. It is preferable to make the thickness of the intermediate layer 41 formed thicker than other regions.

  Here, the thickness of the intermediate layer 41 is about 0.1 to 1 times the height of the inclined portion 31a in the inclined portion 31a of the first protective layer 31 and its vicinity, and in other regions (flat portions). Is preferably about 0.01 to 0.1 times the height of the inclined portion 31a. For example, when the height of the inclined portion 31a of the first protective layer 31 is 1 μm, the film thickness of the intermediate layer 41 is 0.02 μm in the flat portion, and is about 0.02 μm so as to have a forward tapered inclination around the inclined portion 31a. Set to 5 μm. If it does so, the level | step difference mitigation part 40 can be obtained with the desired shape shown by FIG.4 (b), when the next etching process is implemented.

  The intermediate layer 41 can be formed by adjusting the viscosity of the constituent material of the intermediate layer 41 to be used, application conditions (for example, the number of spin coating rotations), and the like. For example, it is possible to form the intermediate layer 41 in the shape shown in FIG. 4A by setting the viscosity as a material to be applied to about 1 cP to 10 cP and setting the spin coat rotation speed to a range of 1000 rpm to 5000 rpm. .

(4) Etching Step Next, the intermediate layer 41 is etched by an anisotropic etching method to form the step relief portion 40 (etching step). Specifically, as shown in FIG. 4B, the intermediate layer 41 is anisotropically etched using a reactive ion etching (RIE) apparatus. Thereby, the step relief portion 40 is formed in the inclined portion 31 a of the first protective layer 31. In this step, anisotropic etching that can increase the etching rate in the direction perpendicular to the substrate surface is employed. Thereby, the inclined surface of the level | step difference relaxation part 40 can be closely approached to the inclined surface of the intermediate | middle layer 40. FIG. The etching gas used in this step can be appropriately selected according to the constituent material of the intermediate layer 41. Examples thereof include oxygen gas and CF ₄ gas. When the intermediate layer 41 is formed using polycarbonate as in the present embodiment, oxygen gas can be used as the etching gas. In this step, the etching time is set so that the intermediate layer 41 formed in the flat region of the first protective layer 31 can be removed.

(5) Step of forming second protective layer Next, the second protective layer 32 having a function of suppressing the permeation of moisture and oxygen is formed on the first protective layer 31 and the step relief portion 40 (second). Step of forming protective layer). Here, the constituent material of the second protective layer 32 may be the same as or different from the constituent material of the first protective layer 31. Specifically, silicon nitride (SiN _x ) or the like is used. Moreover, as a formation method of the 2nd protective layer 32, the same method as the formation method of the 1st protective layer 31 may be sufficient, and a different method may be sufficient. Specifically, a CVD method or the like is used.

  At this time, the inclination angle of the inclined portion 31a of the first protective layer 31 is relaxed by the step relief portion 40, and the sectional shape of the inclined portion 31a and the vicinity thereof is a forward tapered shape. For this reason, even if the second protective layer 32 is formed with a film thickness thinner than that of the first protective layer 31, the second protective layer 32 having a sealing property equal to or higher than the sealing property of the first protective layer 31. Can be formed.

  As described above, in the present invention, the film of the second protective layer 32 provided on the first protective layer 31 by selectively providing the step relief portion 40 around the inclined portion 31a of the first protective layer 31. The performance is improved as compared with the first protective layer 31. Specifically, when a defect occurs in the first protective layer 31, the step reducing member 40 is provided around the defect. Thereby, when forming the 2nd protective layer 32, it can prevent that the defect of the 2nd protective layer 32 generate | occur | produces in the area | region where the said defect exists. Further, in order to remove the intermediate layer 40 provided on the region where the first protective layer 31 is formed flat (having no defects) in the etching process, the first protective layer 31 is interposed between the first protective layer 31 and the second protective layer 32. There is no intermediate layer 40 capable of diffusing moisture and oxygen. Therefore, even if a defect occurs in the second protective layer 32, it is possible to prevent moisture and oxygen from reaching this defect (the inclined portion 31a) of the first protective layer 31. Therefore, since it becomes possible to reduce dark spots at the stage where two protective layers (first protective layer 31 and second protective layer 32) are provided, it is less necessary to receive the protective layer. For this reason, a highly reliable display device can be produced with a high yield. Furthermore, the display device of the present invention can obtain high sealing performance by combining the first protective layer 31, the step relief portion 40, and the second protective layer 32. For this reason, a display device with high reliability can be obtained even if the protective layers (31, 32) are relatively thin.

  The display device 1 of FIG. 1 was produced by the method described below.

(1) Substrate with electrode First, the substrate 10 on which the TFT and the first electrode 21 were formed was washed and then placed in a vacuum atmosphere chamber. Then, a baking process was performed in a vacuum atmosphere, and the substrate 10 was pretreated with oxygen plasma.

(2) Step of forming organic compound layer Next, a hole transport layer was formed on the entire surface of the display region by a vacuum deposition method while maintaining a vacuum atmosphere. At this time, the thickness of the hole transport layer was set to about 80 nm. Next, the substrate was transferred to a film formation chamber for forming a red light emitting layer, and after alignment of the evaporation mask having a stripe opening with the substrate, the red light emitting layer was formed. Next, a green light emitting layer and a blue light emitting layer were formed in the same manner. The layers other than the light emitting layer constituting the organic compound layer 22 were formed in each film forming chamber as a common layer in the display region.

(3) Second Electrode Formation Step Next, an Ag alloy was formed on the organic compound layer 22 to form the second electrode 23. At this time, the film thickness of the second electrode 23 was set to 25 nm. The second electrode 23 is a semi-transmissive conductive layer.

(4) Step of forming first protective layer Next, a silicon nitride (SiN _x ) film was formed on the second electrode 23 by the CVD method to form the first protective layer 31. At this time, the film thickness of the first protective layer 31 was 1.0 μm. In consideration of thermal damage to the organic compound layer 22, the temperature condition of the substrate 10 when forming the first protective layer 31 was set to 110 ° C. Further, the light transmittance (λ = 430 nm) of the first protective layer 31 formed in this example was 90% or more, and the film stress was about 150 MPa. Therefore, the influence on the light extraction efficiency of the display device which can be caused by providing the first protective layer 31 can be suppressed, and problems due to film peeling can be prevented.

(5) Step of forming intermediate layer Next, the substrate 10 formed up to the first protective layer 31 was put into a chamber in a nitrogen atmosphere without being exposed to the atmosphere. In this chamber, the dew point is controlled to −80 ° C. and the oxygen concentration is controlled to 10 ppm or less. Next, in this environment, a solution prepared by mixing polycarbonate and toluene (concentration: 0.3% by weight) was dropped and applied on the first protective layer 31 to form a coating film. Next, the substrate 10 was placed under reduced pressure heating conditions to remove the solvent in the coating film. Thus, the intermediate layer 41 was obtained. Note that the film thickness distribution of the intermediate layer 41 is as shown in FIG. That is, the thickness of the intermediate layer 41 is relatively thick in the inclined portion 31 a of the first protective layer 31, and the cross-sectional shape around the inclined portion 31 a is a forward tapered shape due to the intermediate layer 41. More specifically, the thickness of the intermediate layer 41 in the flat region where the foreign matter 51 does not exist is 20 nm, while the inclined portion 31a (height: 1 μm, inclined angle: 90 ° C. of the first protective layer 31. The thickness of the intermediate layer 41 is about 400 nm.

(6) Etching Step Next, using a reactive ion etching (RIE) apparatus, as shown in FIG. 4B, the intermediate layer 41 was removed by anisotropic etching to form the step relief portion 40. In addition, since oxygen gas was used as etching gas, the 1st protective layer 31 was hardly etched. The etching time was set so that the intermediate layer 41 having a thickness of 20 nm formed in the flat region of the first protective layer 31 was completely removed. As a result, the level | step difference relaxation part 40 had a cross-sectional forward taper shape, and the maximum thickness was about 380 nm.

(7) Step of Forming Second Protective Layer Next, as shown in FIG. 4C, silicon nitride (SiN _x ) is formed on the step relief portion 40 and the first protective layer 31 by the CVD method. Thus, the second protective layer 32 was formed. At this time, the film thickness of the second protective layer 32 was set to 0.5 μm. In consideration of thermal damage to the organic compound layer 22, the temperature condition of the substrate 10 when forming the first protective layer 31 was set to 100 ° C. The light transmittance (λ = 430 nm) of the second protective layer 32 formed in this example was 90% or more, and the film stress was about 150 MPa. Therefore, the influence on the light extraction efficiency of the display device that can be caused by providing the second protective layer 32 can be suppressed, and problems due to film peeling can be prevented.

  Thus, a display device was obtained. When the display device obtained here was exposed to a temperature of 60 ° C. and 90% RH for 1000 hours, the incidence of dark spots in the display device was evaluated. As a result, it was found that the occurrence rate of dark spots can be reduced to 4%.

  On the other hand, as a comparative example, the occurrence rate of dark spots was evaluated under the same conditions for a display device formed by omitting the formation process (intermediate layer formation process, etching process) of the step relief portion 40. As a result, the incidence of dark spots was about 30%.

  As in Example 1, the display device shown in FIG. 1 was produced.

(1) Substrate with electrode A substrate with an electrode having the first electrode 21 treated in the same manner as in (1) of Example 1 was prepared.

(2) Formation Step of Organic Compound Layer An organic compound layer 22 was formed by the same method as (2) of Example 1.

(3) Second Electrode Formation Step A second electrode 23 was formed by the same method as in Example 1 (3).

(4) Step of forming first protective layer The first protective layer 31 was formed by the same method as (4) of Example 1.

(5) Step of forming intermediate layer First, on the first protective layer 31, a silicon oxide film was formed to form an etching stop layer. At this time, the film thickness of the etching stop layer was set to 0.5 μm.

  Next, the substrate 10 on which the first protective layer 31 and the etching stop layer were formed was put into a nitrogen atmosphere chamber without being exposed to the atmosphere. In this chamber, the dew point is controlled to −80 ° C. and the oxygen concentration is controlled to 10 ppm or less. Next, in this environment, a solution (concentration: 5% by weight) prepared by mixing polysilazane and dibutyl ether was dropped and applied on the etching stop layer to form a coating film. Next, the substrate 10 was placed under reduced pressure heating conditions to remove the solvent in the coating film. Thus, the intermediate layer 41 was obtained. Note that the film thickness distribution of the intermediate layer 41 is as shown in FIG. That is, the thickness of the intermediate layer 41 is relatively thick in the inclined portion 31 a of the first protective layer 31, and the cross-sectional shape around the inclined portion 31 a is a forward tapered shape due to the intermediate layer 41. More specifically, the thickness of the intermediate layer 41 in the flat region where the foreign matter 51 does not exist is 20 nm, while the inclined portion 31a (height: 1 μm, inclined angle: 90 ° C. of the first protective layer 31. The thickness of the intermediate layer 41 is about 600 nm.

(6) Etching Step Next, using a reactive ion etching (RIE) apparatus, the intermediate layer 41 was removed by anisotropic etching to form the step relief portion 40. In this example, CF ₄ gas was used as the etching gas. Here, the etching rate of silicon oxide constituting the etching stop layer exposed to the etching gas (CF ₄ gas) is about 1/20 of that of polysilazane constituting the intermediate layer 40. The etching time was set such that the 20 nm thick intermediate layer 41 formed in the flat region of the first protective layer 31 was completely removed. As a result, the level | step difference relaxation part 40 had a cross-sectional forward taper shape, and the maximum thickness was about 580 nm.

(7) Step of forming second protective layer The second protective layer 32 was formed by the same method as (7) of Example 1.

  Thus, a display device was obtained. When the display device obtained here was exposed to a temperature of 60 ° C. and 90% RH for 1000 hours, the incidence of dark spots in the display device was evaluated. As a result, it was found that the occurrence rate of dark spots can be reduced to 4%.

  1: Display device, 10: Substrate, 20: Organic light emitting element, 21: First electrode, 22: Organic compound layer, 23: Second electrode, 31: First protective layer, 32: Second protective layer, 40: Step Relaxation part, 41: Intermediate layer

Claims (4)

Forming a first electrode, an organic light emitting layer, and a second electrode on the substrate in this order;
Forming a first protective layer so as to cover the organic light emitting element; and
Forming an intermediate layer on the first protective layer; and
An etching step of selectively forming a step relief portion around the inclined portion of the first protective layer by etching the intermediate layer;
And a second protective layer forming step of forming a second protective layer on the first protective layer and on the step relief portion.   The method for manufacturing a display device according to claim 1, wherein the forming step of the intermediate layer is performed by a coating method.   The method for manufacturing a display device according to claim 1, wherein the etching step is performed by an etching method having anisotropy. A substrate,
An organic light emitting device formed on the substrate;
A first protective layer covering the organic light emitting device;
A second protective layer provided on the first protective layer and covering the organic light emitting element,
The first protective layer has an inclined portion due to foreign matter existing on the organic light emitting element,
A step relief portion is selectively provided around the inclined portion,
The display device, wherein the second protective layer covers the first protective layer and the step relief portion.

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